Variable-speed-drive system for a grid blower

ABSTRACT

A drive system for a grid blower of a vehicle is provided. The system includes: an electrical bus, a grid of resistive elements connected to the electrical bus, the grid of resistive elements configured to thermally dissipate electrical power generated from braking of the vehicle, the electrical power being transmitted on the electrical bus to the grid of resistive elements, an electrical power modulation device configured to modify electrical power received from at least one of the electrical bus and the grid of resistive elements, and a grid blower motor coupled to an output of the electrical power modulation device, wherein a speed of the grid blower motor varies based on the electrical power that has been modified by the electrical power modulation device.

BACKGROUND

A propulsion system may include one or more traction motors to generatetractive output. For example, a propulsion system having one or moretraction motors may be utilized in an off-highway vehicle (OHV)application, locomotive application, a marine application, a drillingapplication, etc. In one example, a locomotive vehicle having tractionmotors may perform dynamic braking in conjunction with air braking inorder to slow the locomotive vehicle. By utilizing dynamic braking, thebrake load on the air brakes may be reduced which, in turn, may reducethe wear on the air brakes thus extending their useful life.

During dynamic braking operations, the traction motors may generateelectrical power that may be transmitted to a grid of resistive elementswhich may dissipate the electrical power in the form of heat. As dynamicbraking operations are performed, the temperature of the grid ofresistive elements may increase. Accordingly, a blower may be utilizedto provide forced-air cooling to the grid of resistive elements. In oneexample, the blower is powered by a motor that is coupled to taps acrossthe grid of resistive elements. As such, the blower operates wheneverthere is electrical power on the grid of resistive elements, such asduring a dynamic braking operation. Since the blower is directly poweredby electrical power from the grid of resistive elements, additionalelectrical power need not be generated specifically to power the blower.

However, various issues may arise with the above describedconfiguration. As a first example, since the blower motor is directlyconnected to the taps across the resistive elements of the grid, thespeed of the blower depends on the electrical power on the grid ofresistive elements. As another example, the blower accelerates at a highrate whenever electrical power is suddenly applied to the grid ofresistive elements, thereby producing high transients which may resultin increased noise, vibration, harshness, and stress on the equipment.

BRIEF DESCRIPTION OF THE INVENTION

Accordingly, to address at least some of the above issues, a drivesystem for a grid blower of a vehicle is described herein. For example,in one embodiment, the system comprises: an electrical bus; a grid ofresistive elements connected to the electrical bus, the grid ofresistive elements configured to thermally dissipate electrical powergenerated from braking of the vehicle, the electrical power beingtransmitted on the electrical bus to the grid of resistive elements; anelectrical power modulation device configured to modify electrical powerreceived from at least one of the electrical bus and the grid ofresistive elements; and a grid blower motor coupled to an output of theelectrical power modulation device, wherein a speed of the grid blowermotor varies based on the electrical power that has been modified by theelectrical power modulation device.

Since the electrical power supplied to the grid blower motor may bevaried from the electrical power on the grid of resistive elements, itis possible to decouple the speed of the grid blower from the electricalpower on the grid of resistive elements. As such, the speed of the gridblower may be varied as desired. For example, the voltage provided tothe grid blower motor may be increased in order to increase the rate ofacceleration, and/or speed, of the grid blower beyond what theelectrical power on the grid of resistive elements could provide. Asanother example, the grid blower speed may be controlled withoutchanging the braking power dissipated in the grid of resistive elements.The varied operation of the grid blower may enhance the forced-aircooling effects on the grid of resistance elements, thereby increasingthe useful life of the grid of resistive elements and/or increasing thebraking capabilities of the traction system.

Furthermore, speed control may be used to reduce stress and/or wear ofthe grid blower. For example, the acceleration or deceleration of thegrid blower may be controlled between speed levels to limit the stressfrom inertial forces. As another example, throughout frequently varyingoperation conditions, such as varying dynamic braking power between highand low levels where different levels of electrical power flow acrossthe grid of electrical elements, the grid blower speed may be heldsubstantially constant. Due to the substantially constant speed ofoperation, the centrifugal force related stress cycles on the gridblower impeller or fan blades may be reduced. Accordingly, the life ofthe grid blower may be extended.

Furthermore, under some conditions, it may be desirable to reduce theaudible noise output level of the locomotive vehicle, and moreparticularly, the grid blower. Therefore, the voltage provided to thegrid blower motor may be reduced in order to reduce the speed of thegrid blower, thereby reducing the audible noise output level of the gridblower without changing the power dissipated in the braking grids. In anexample where multiple grid blowers powered by multiple inverters areimplemented in a traction system, the blower impeller blade phase orfrequency relationship may be controlled to reduce or minimize audiblenoise output or reduce monotonic noise.

It should be understood that the summary above is provided to introducein simplified form a selection of concepts that are further described inthe detailed description. It is not meant to identify key or essentialfeatures of the claimed subject matter, the scope of which is defineduniquely by the claims that follow the detailed description.Furthermore, the claimed subject matter is not limited toimplementations that solve any disadvantages noted above or in any partof this disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be better understood from reading thefollowing description of non-limiting embodiments, with reference to theattached drawings, wherein below:

FIG. 1 shows a schematic diagram of a locomotive vehicle system;

FIG. 2 shows a schematic diagram of one embodiment of a grid blowerdrive configuration;

FIG. 3 shows a schematic diagram of another embodiment of a grid blowerdrive configuration;

FIG. 4 shows a schematic diagram of yet another embodiment of a gridblower drive configuration;

FIG. 5 shows a line graph comparing the performance of a grid blowerconnected to the grid blower drive configuration of FIG. 2 versus a gridblower directly connected across the resistive elements of a grid in ahigh air density environment;

FIG. 6 shows a line graph comparing the performance of a grid blowerconnected to the grid blower drive configuration of FIG. 2 versus a gridblower directly connected across the resistive elements of a grid in alow air density environment;

FIG. 7 shows a flowchart of an example audible noise level controlmethod;

FIG. 8 shows a schematic diagram of an embodiment of an inverter-motorcoupling configuration; and

FIG. 9 shows a flowchart of an example electrical power distributionmethod utilizing the inverter-motor coupling configuration of FIG. 8.

DETAILED DESCRIPTION

The subject matter disclosed herein generally relates to propulsionsystems utilizing tractive effort. In particular, the subject matterrelates to mechanisms that may be utilized to aid in heat dissipationfrom electrical power dissipation grids of a locomotive vehicle havingtraction motors. FIG. 1 schematically shows an example of a locomotivevehicle system 100. Typically, the locomotive vehicle system may be adiesel-electric locomotive that includes a diesel engine. However, itwill be appreciated that engine configurations other than a dieselengine may be implemented in the locomotive vehicle system, such as agasoline engine, for example. In some embodiments, the locomotivevehicle system may be powered by way-side power and the engine may beomitted (e.g., electric locomotives).

The locomotive vehicle system 100 includes an engine 102 that may beconfigured to generate torque output that drives a converter 104. Theconverter 104 may produce electrical power that may be provided tovarious electrical components by an electrical bus 106. In someembodiments, the converter may include one or more alternators thatproduce alternating current (AC) electrical power. In some embodiments,the converter may include one or more rectifiers that produce directcurrent (DC) electrical power. Further, in some embodiments, theconverter may include both one or more alternators and one or morerectifiers. Correspondingly, in some embodiments, the electrical bus maybe a DC electrical bus. Further, in some embodiments, the electrical busmay be an AC electrical bus.

One or more electrical power modulation device(s) 108 may receiveelectrical power from the electrical bus 106. The electrical powermodulation device(s) 108 may be configured to modify the electricalpower received from the electrical bus 106 to a suitable form to beprovided to electrical components of the locomotive vehicle system. Inparticular, the electrical power modulation device may be configured tomodify a parameter of the electrical power such as voltage or frequency,for example. In some embodiments, the electrical power modulation devicemay include an inverter. In one example, the inverter converts DCelectrical power to AC electrical power, among other modifications. Insome embodiments, the electrical power modulation device may include aconverter. In one example, the converter modifies the voltage of DCelectrical power from the DC electrical bus to a different voltage inorder to supply the DC electrical power to a DC electrical component.

A traction motor 110 may receive electrical power from the electricalpower modulation device(s) 108 to provide tractive power in order topropel the locomotive. For the purpose of simplicity, only one tractionmotor is illustrated. However, it will be appreciated that a pluralityof traction motors may provide tractive power to propel the locomotivevehicle using electrical power provided from the electrical bus.

Furthermore, the traction motor 110 may be configured to act as agenerator to provide dynamic braking to slow the locomotive. Inparticular, during dynamic braking, the traction motor 110 may providetorque in a direction that is opposite from the rolling direction of thelocomotive which, in turn, generates electrical power that may be sentthrough the electrical bus 106 to a grid 112 where the electrical powermay flow across a plurality of resistive elements of the grid and may bedissipated in the form of heat.

In some embodiments, the electrical bus may include one or more switches(not shown) that may be adjusted to control the transmission ofelectrical power. For example, during dynamic braking a state of aswitch may be changed to send electrical power generated by the tractionmotor to the grid of resistive elements in order to be thermallydissipated.

In one particular example, the grid includes stacks of resistiveelements connected in series to the electrical bus. The stacks ofrestive elements may be positioned proximate to the ceiling of a hood ofthe locomotive in order to facilitate air cooling and heat dissipationfrom the grid. Alternatively, other suitable grid configurations may beimplemented.

Furthermore, during operation of the locomotive, the temperature of thegrid and the traction motor may increase. Accordingly, the grid and thetraction motor may be force-air cooled. In particular, a traction motorblower 114 may blow air to cool the traction motor 110. The tractionmotor blower 114 may be powered by a traction motor blower motor 116that is configured to receive electrical power from the electrical powermodulation device(s) 108 which modifies electrical power received fromthe electrical bus 106. Likewise, a grid blower 118 may blow air to coolthe grid 112. The grid blower 118 may be powered by a grid blower motor120 that is configured to receive electrical power from the electricalpower modulation device(s) 108 which modifies electrical power receivedfrom the electrical bus 106. It will be appreciated that locomotivevehicle system 100 may include plural grid blowers to cool one or moreresistive element grid(s).

Furthermore, other components of the vehicle locomotive system 100 maybe force-air cooled. In particular, an auxiliary blower 122 may blow airto cool an auxiliary component 124. The auxiliary blower 122 may bepowered by an auxiliary blower motor 126 that is configured to receiveelectrical power from the electrical power modulation device(s) 108which modifies electrical power received from the electrical bus 106.

In some embodiments, the auxiliary component may receive electricalpower from the electrical bus. For example, the auxiliary component mayinclude a compression device configured to compress intake air, such asa supercharger or a turbocharger. However, the auxiliary component neednot receive electrical power. For example, the auxiliary component mayinclude a radiator for cooling the diesel engine. In some embodiments,the auxiliary blower may be used to cool intake air prior to entering acompression device in order to improve engine efficiency.

It will be appreciated that the locomotive vehicle system may include aplurality of different electrical power modulation devices, each ofwhich may supply electrical power to a different component.Alternatively or optionally, the locomotive vehicle system may includeone or more electrical power modulation device(s) connected to a switchthat may be controlled to selectively provide electrical power todifferent components connected to the switch.

Locomotive vehicle system 100 may include a controller 128 configured tocontrol components of the locomotive vehicle system (e.g., engine,traction motor, blower drives, etc.). The controller 128 may include amicrocomputer having a processor and electronic storage media forexecuting programs and storing calibration and control data. Thecontroller 128 may receive signals from sensors coupled to components ofthe locomotive vehicle system and may perform feedback and/orfeedforward control based on the signals. Examples of signals that maybe received by the controller include engine speed, motor speed, blowerspeed, engine temperature, motor temperature, grid temperature, ambienttemperature, engine load, motor load, voltage, current, etc.Furthermore, the controller 128 may be configured to vary blower speedbased on various operating conditions by adjusting the state ofelectrical power modulation devices that provide electrical power toblower motors. In particular, an electrical power modulation device mayinclude a plurality of switches, the state of which may be toggled tomodulate electrical power. For example, an electrical power modulationdevice may be controlled to raise/lower voltage, increase/decreasefrequency, adjust phase, etc.

FIG. 2 schematically shows one embodiment of a grid blower driveconfiguration of the present disclosure. In the illustrated embodiment,a grid 200 includes three resistive elements (R1, R2, R3) that areconnected in series to a DC electrical bus 202. It will be appreciatedthat the grid may include virtually any suitable number of resistiveelements to dissipate electrical power in the form of heat.

As discussed above, during dynamic braking, electrical power may begenerated as a result of the traction motor generating torque to slowthe locomotive. The generated electrical power may be transferred fromthe traction motor through the DC bus to the resistive elements of thegrid. Consequently, the temperature of the resistive elements of thegrid may increase up to a temperature of approximately six hundreddegrees Celsius or more, for example. A blower (not shown) may beoperated to blow air at the grid in order to aid in dissipation of theheat. The blower may be powered by a grid blower drive 204 that includesan AC grid blower motor 208. The AC grid blower motor 208 may be coupledto an inverter 206 that may be coupled to taps on the DC bus 202. Theinverter 206 may be configured to provide variable frequency and/orvariable voltage output to the AC grid blower motor 208. As a particularexample, the inverter may be a DC to three phase inverter having threephase output. It will be appreciated that, in the illustrated embodimentof the drive configuration, since the inverter is directly connected tothe DC bus the grid blower motor may be powered by the entire voltage onthe DC bus, if desired, in order to operate the grid blower at a highspeed.

Since the AC grid blower motor receives electrical power from theinverter rather than directly from across the resistors, the operationof the grid blower motor and correspondingly the speed of the gridblower may be decoupled from the electrical power on the grid. In otherwords, the speed of the grid blower may be operated and adjustedindependent of the amount of electrical power on the grid. By enablingindependent speed control of the grid blower motor, the accelerationand/or speed of the grid blower may be varied regardless of a voltagelevel on the grid of resistive elements. Accordingly, the grid blowerspeed may be controlled to enhance cooling of the grid which may extendthe usable lifetime of the grid as well as increase the brakingcapability of the locomotive.

Furthermore, due to the variable speed control of the grid blower, undersome conditions, the speed of the grid blower may be advantageouslyreduced or maintained at a substantially constant speed. For example,grid blower speed may be reduced to reduced inertial stress on impelleror fan blades of the grid blower in order to extend the useful lifetimeof the grid blower. As another example, the speed of the grid blower maybe reduced in order to reduce the audible noise level of the grid blowerto a desired audible noise level. In contrast, a grid blower driveconfigured so that speed of the grid blower is based on an amount ofelectrical power across the grid may be incapable of voluntarilyreducing the speed of the grid blower. Grid blower control strategiesfor managing audible noise will be discussed in further detail belowwith reference to FIG. 7. Further, the speed of the grid blower may bemaintained at a substantially constant speed even as electrical power onthe grid or bus varies in order to reduce stress on the grid blower fromcentrifugal forces.

FIG. 3 schematically shows another embodiment of a grid blower driveconfiguration of the present disclosure. In the illustrated embodiment,a grid 300 includes three resistive elements (R1, R2, R3) that areconnected in series to a DC electrical bus 302. A grid blower (notshown) may be provided to generate forced-air cooling of the grid 300.The grid blower may be powered by a grid blower drive 304 that includesan inverter 306 that may be connected to taps across the grid 300. Theinverter 306 may be configured to provide variable frequency and/orvariable voltage AC output to an AC grid blower motor 308 that iscoupled to an output of the inverter 306. As a particular example, theinverter may be a DC to three phase inverter having three phase ACoutput. It will be appreciated that, in this embodiment of the driveconfiguration, since the inverter is connected to taps across theresistance of the grid, the amount of current provided to the inverterand/or the grid blower motor may increase. Further, since the current isincreased, a different AC grid blower motor may be used for forced-aircooling of the grid. For example, a larger and/or more powerful AC gridblower motor, a lower voltage motor, or standard voltage (insulationtype) motor may be employed.

Note, in the illustrated embodiment, the inverter may be connectedacross one or some of the resistors of the grid depending on the powerhandling capabilities of the inverter and/or the grid blower motor.

It will be appreciated that by using AC motors in the grid blowerdrives, drive maintenance may be reduced relative to using DC motors. Inparticular, DC motors have commutation brushes that require routinemaintenance. Since AC motors lack commutation brushes reducedmaintenance may be used. Moreover, since AC motors lack commutationbrushes the blowers can be run at higher speeds before beingmechanically limited as compared to DC motors which may be mechanicallylimited by the commutation brushes.

FIG. 4 schematically shows yet another embodiment of a grid blower driveconfiguration of the present disclosure. In the illustrated embodiment,a grid 400 includes three resistive elements (R1, R2, R3) that areconnected in series to a DC electrical bus 402. A grid blower (notshown) may be provided to generate forced-air cooling of the grid 400.The grid blower may be powered by a grid blower drive 404 that includesa DC-to-DC converter 406 that may be connected to taps across the grid400. The DC-to-DC converter 406 may be configured to provide variablevoltage DC output to a DC grid blower motor 408 that is coupled to theoutput of the DC-to-DC converter 406. This example drive configurationmay be implemented as a reduced cost alternative to the above describedembodiments, because the converter and/or the DC grid blower motor maycost less than an inverter and/or an AC grid blower motor. Note thatonly two wires are used to connect the one motor in series, but aconfiguration having three wires may be used for non series machine likeparallel machines, or separately excited motors. Further note, a tapchange between various voltage levels (e.g. a high voltage tap and a lowvoltage tap) may be utilized to achieve at least some of the variablespeed control functionality.

FIG. 5 shows an example performance comparison of equal horsepower gridblower motors conducted in a high air density environment. The speed ofa first motor is controlled independent of a grid voltage and the speedof a second motor is dependent on the grid voltage. For this examplecomparison, the first grid blower motor was connected according to thedrive configuration shown in FIG. 2 and the second motor was directlyconnected to taps across the resistance elements of a grid. Accordingly,the operation of the first motor was independent of an amount ofelectrical power on the grid whereas the operation of the second motorwas dependent on the amount of electrical power on the grid. Line graph500 compares speed of the grid blower motors in revolutions per minute(RPM) along a Y-axis versus voltage in DC volts along an X-axis. Theperformance of the first grid blower motor is indicated by a solid lineand the performance of the second grid blower motor is indicated by adashed line.

The line graph 500 clearly shows that the first grid blower motorachieves a higher speed relative to the second grid blower motor whenoperating at the same voltage, thus indicating that the first motor maybe independently controlled to accelerate faster than the second motorcan accelerate based on the electrical power on the grid. The firstmotor operational acceleration advantage exists all the way until theoperating speed performance limit of the grid blower motors is reached(at approximately 3400 RPM and 1400 VDC). Accordingly, due to thequicker acceleration, the first grid blower motor may achieve a maximumoperating speed at a much lower voltage (approximately 800 VDC) ascompared to that of the second grid blower motor (approximately 1400VDC). Accordingly, the independently controlled grid blower may haveenhanced forced-air cooling that may extend the operational lifetime ofthe grid.

Moreover, the operational advantages of the first grid blower motor ascompared to the second grid blower motor are even more pronounced in alow air density environment. FIG. 6 shows an example performancecomparison of the equal horsepower grid blower motors of FIG. 5conducted in a low air density environment in a line graph 600. Similarto the high air density example, the first grid blower motor achieves ahigher speed relative to the second grid blower motor when operating atthe same voltage, due to due to decoupled ratio of motor voltage andgrid resistance voltage and also due to frequency control of theinverter of the first grid blower motor. However, due to the low airdensity, the first grid blower motor is capable of achieving a highermaximum speed than the second grid blower motor. In a particular casewhere the second grid blower motor is a DC motor, the speed capabilityof second grid blower motor may be mechanically restricted by thecommutation brushes of the DC grid blower motor whereas the first motormay be an AC grid blower motor that operates without commutation brushesand has a higher mechanical threshold. Accordingly, the AC grid blowermotor may maintain an operational advantage over the DC grid bloweracross a greater operational range in a low air density environment.

It will be appreciated that the comparisons illustrated in FIGS. 5 and 6are examples. Further, note that a comparison of a DC motor connectedaccording to the above described drive configuration may have anoperational advantage over a DC motor that is directly connected to thegrid.

In general, the grid blower may be operated at as high of a speed aspossible in order to generate maximum cooling of the grid. However,under some conditions, it may be desirable to operate the grid blowermotor at a different speed. For example, the grid blower motor speed maybe adjusted based on an audible noise level generated as a result ofnoise, vibration, harshness produced by the grid blower. In oneparticular example, a locomotive may be required to operate below anaudible noise threshold level while traveling through different areas,such as a residential area or a mountain pass. In order to meet theaudible noise threshold various components of the locomotive, includingthe grid blower, may be adjusted in order to reduce the audible soundlevel. FIG. 7 shows a flowchart of an example method for controllingaudible noise output of a locomotive based on the audible noise outputcapability of a grid blower. A flowchart 700 begins at 702, where themethod may include assessing operating conditions of the locomotivevehicle system. Nonlimiting examples of operating conditions that may beassessed include vehicle travel speed, engine speed, motor speed,ambient temperatures, component temperatures, air density, etc.

At 704, the method may include assessing the total audible noise leveloutput of components of the locomotive based on the assessed operatingconditions. In one example, an audible noise level for each component ofthe locomotive may be determined based on one or more given operatingparameters of the component. In particular, the audible noise level ofeach component may be mapped to the one or more operating parameters ina look-up table stored in memory. Thus, a noise level for each componentmay be determined from the look-up table in order to assess the totalaudible noise level of the locomotive.

At 706, the method may include setting an audible noise threshold. Theaudible noise threshold may indicate a level of audible noise thatshould not be exceeded by the total audible noise level generated by theoperation of the locomotive. In some embodiments, the audible noisethreshold may be set based on a location of the locomotive. For example,the threshold may be set to a high audible noise level when thelocomotive is traveling through rural areas and the threshold may be setto a low audible noise level when the locomotive is traveling throughurban areas. In one example, the threshold level based on location maybe set manually. In another example, the location may be inferred basedon the speed of the locomotive and the threshold may be set based on thespeed. In yet another example, the audible noise threshold may be basedon global positions system coordinate information or based on anothersignal received by the locomotive, such as from extended radio frequencysignals sent from sensors proximate to the railroad track. For example,a sensor at a railroad crossing or a bridge may send a signal to thelocomotive. In yet another example, the threshold may be based on aconfiguration of the locomotive. For example, the threshold may be setbased on the number of grid blowers and/or other equipment currentlyoperating.

At 708, the method may include comparing the total audible noise levelof the locomotive with the threshold audible noise level. If it isdetermined that the total audible noise level of the locomotive exceedsthe threshold audible noise level, the flowchart moves to 710.Otherwise, the flowchart ends.

At 710, it has been determined that the total audible noise levelexceeds the threshold audible noise level. Accordingly, the operationalaudible noise level of the locomotive should be reduced. Therefore, themethod may include comparing the grid blower audible noise leveladjustment capability to the audible noise level that exceeds thethreshold audible noise level. In other words, the comparison determinesif a change in grid blower operation is capable of lowering the totalaudible noise level below the threshold audible noise level. If the gridblower audible noise level adjustment capability is greater than theaudible noise level that exceeds the threshold audible noise level theflowchart moves to 712. Otherwise, the grid blower audible noise leveladjustment capability is less than the audible noise level that exceedsthe threshold audible noise level and the flowchart moves to 714.

At 712, the method may include adjusting the speed of the grid blowermotor in order to reduce the audible noise level of the grid blower sothat the total audible noise level of the locative may be reduced tobelow the threshold audible noise level.

At 714, the grid blower audible noise level adjustment capability isless than the audible noise level that exceeds the threshold audiblenoise level, so the method may include adjusting the operation of alocomotive component other than the grid blower in order to reduce thetotal audible noise level of the locomotive to below the thresholdaudible noise level. For example, the output of the engine and/or thetraction motor may be adjusted to reduce the audible noise level of thelocomotive to below the threshold audible noise level.

Since the speed of the grid blower does not depend on the electricalpower on the grid, the grid blower may be adjusted to achieve variousoperating objectives. In particular, under some conditions, the speed ofgrid blower may be adjusted to a high speed to provide enhancedforced-air cooling that would not be achieved as quickly if theoperation of the grid blower was dependent on the electrical power onthe grid. Moreover, under some conditions, the speed of the grid blowermay be adjusted to reduce a level of audible noise in order to meet adesired audible noise level.

FIG. 8 schematically shows an example of an inverter-motor drivecoupling configuration. The inverter-motor coupling configurationutilizes a transfer switch to enable two different inverters to eachselectively provide electrical power to one of three different motors ofthe locomotive vehicle system based on operating conditions. Theinverter-motor coupling configuration 800 includes an auxiliary blowerinverter 802 and a traction motor blower inverter 804 coupled torespective inputs of a transfer switch 806. Both of the auxiliary blowerinverter 802 and the traction motor blower inverter 804 may beconfigured to receive DC voltage from a DC power source, such as a DCbus. Further, both of the auxiliary blower inverter 802 and the tractionmotor blower inverter 804 may be configured to invert the DC voltage toAC voltage, and in some cases, may vary the frequency and/or the voltageto a suitable form for one of the motors.

An AC auxiliary blower motor 808, an AC traction motor blower motor 810,and an AC grid blower motor 812 may be coupled to respective outputs ofthe transfer switch 806. The AC auxiliary blower motor 808 may beconfigured to provide electrical power to an auxiliary blower to provideforced-air cooling. It will be appreciated that forced-air cooling maybe provided by the auxiliary blower to cool an auxiliary component ofthe locomotive vehicle system. For example, the auxiliary component mayinclude a radiator blower to cool a radiator of the locomotive vehiclesystem. As another example, the auxiliary component may include anintake air cooler to cool intake air being drawn in for compression by acompression device. The AC traction motor blower motor 810 may beconfigured to provide electrical power to a traction motor blower toprovide forced-air cooling to the traction motor. The AC grid blowermotor 812 may be configured to provide electrical power to a grid blowerto provide forced-air cooling to the grid.

The traction motor blower inverter 804 may be designated for primarilyproviding electrical power to the traction motor blower motor 810, andunder some conditions, may provide electrical power to one of the othermotors connected to the transfer switch 806. Similarly, the auxiliaryblower inverter 802 may be designated for primarily providing electricalpower to the auxiliary blower motor 808 of an auxiliary component of thelocomotive vehicle system, and under some conditions, may provideelectrical power to one of the other motors connected to the transferswitch 806.

It will be appreciated that the above described configuration may bemodified to include additional blower motors and/or invertersselectively connected via one or more switches without departing fromthe scope of the present disclosure. In some embodiments, one or more ACblower motors may be replaced by a DC motor connected to a chopper orspeed control circuit.

FIG. 9 shows a flowchart of an example method for distributingelectrical power by controlling the transfer switch of FIG. 8 based onoperating conditions of the locomotive vehicle system. Moreparticularly, the electrical power may be selectively distributed fromthe inverters to the motors based on an operating mode of the locomotivevehicle system. A flowchart 900 begins at 902, where the method mayinclude assessing operating conditions. Assessing the operatingconditions may include receiving signals from sensors and calculatingvarious operating parameters based on the signals from the sensors. Theoperating parameters may include, but are not limited to, engine load,traction motor load, heat dissipation grid load, etc. Further, assessingthe operating parameters may be performed in view of the current systemconfiguration. The system configurations may include the enginetransferring electrical power to the traction motors, the enginetransferring at least a portion of electrical power to the grids, thetraction motors supplying at least a portion of electrical power to thegrids. The assessed operating conditions may be used to detect a mode ofoperation of the locomotive vehicle system.

At 904, the method may include detecting if the locomotive vehiclesystem is operating in a first mode, such as a motoring mode. Themotoring mode may include operation of the engine to generate electricalpower for the traction motor so that the traction motor may generatetorque output to propel the locomotive vehicle system. If the motoringmode is detected, the flowchart moves to 906. Otherwise, the motoringmode is not detected and the flow chart moves to 910.

At 906, the method may include connecting the auxiliary blower inverterwith the auxiliary blower motor. It will be appreciated that operationof the auxiliary blower may correspond to engine operation, in someexamples. In one example, during the motoring mode, the auxiliary blowermay be used for forced air-cooling of an auxiliary component such as theradiator which may used to dissipate engine heat during engineoperation. In another example, during motoring mode, the auxiliaryblower may be used for cooling of intake air to improve combustionefficiency of the engine.

At 908, the method may include connecting the traction motor blowerinverter with the traction motor blower motor. During the motoring mode,since the traction motor is operational, the traction motor blower maybe provided with electrical power in order to provide forced-air coolingto the traction motor. During the motoring mode, since the engine andtraction motors are operational and little or no electrical power isprovided to the grid, operation of the blowers associated with theengine and traction motor may be prioritized over the grid blower.

At 910, the method may include detecting if the locomotive vehiclesystem is operating in a second mode, such as a dynamic braking mode.The dynamic braking mode may include operation of the traction motors togenerate torque output to slow the locomotive vehicle system. The torqueoutput may generate electrical power that may be provided to the grid.If the dynamic braking mode is detected, the flowchart moves to 912.Otherwise, the dynamic braking mode is not detected and the flow chartmoves to 916.

At 912, the method may include connecting the auxiliary blower inverterwith the grid blower motor. During the dynamic braking mode, thetemperature of the grid may increase as a result electrical powerproduced by the traction motors flowing across the resistors of thegrid. Accordingly, the grid blower may be provided with electrical powerin order to provide forced-air cooling to the grid.

At 914, the method may include connecting the traction motor blowerinverter with the traction motor blower motor. Since the traction motoris operational during the dynamic braking mode, the traction motorblower may be provided with electrical power in order to provideforced-air cooling to the traction motor. During the dynamic brakingmode, since the traction motor is operational and electrical power isprovided to the grid, operation of the blowers associated with thetraction motor and the grid may be prioritized over the auxiliaryblower.

At 916, the method may include detecting if the locomotive vehiclesystem is operating in third mode, such as a self loading mode. The selfloading mode may include operation of the engine to generate electricalpower to load the locomotive vehicle system for diagnostic purposes, forexample. During the self loading mode, electrical power generated as aresult of engine operation may be provided to the grid and little or noelectrical power may be provided to the traction motors. If the selfloading mode is detected, the flowchart moves to 918. Otherwise, theself loading is not detected and the flow chart ends.

Alternatively, the third mode may be another operating mode where atleast some electrical power is supplied to grid blower via the invertersand substantially no electrical power is supplied to the grid. The thirdoperating mode may be performed for purposes of de-icing the grid ofresistive elements at cold climates as well as to move bearings of thegrid blower for anti-bernelling purposes so lubrication film on thebearings remains effective. In one example, the grid blower may beoperated based on lubrication hardness level such that the grid blowermay be operated to move bearing of the grid blower in order to preventthe lubrication of the bearings from reaching a predetermined level ofhardness.

Additionally, this third mode of operation may be performed after abraking operation, wherein elements of the grid have increased intemperature and the grid blower may be operated to cool the elementseven though no electrical power is being dissipated in the grids. Inprevious systems at power down, the hot elements such as grid elementswhich dissipate power for a period of time continue to radiate and heatthe relatively cooler elements like insulation devices. Since there isno airflow, the insulation devices initially heat up to a highertemperature than during powered operation and then cool down to ambient.Since these type of materials generally degrade quickly at highertemperatures, this transient higher temperature causes a higher failurerate. In this third mode of operation, since the air flow is maintained,this does not happen and the temperature does not increase and thefailure mode is reduced or eliminated.

At 918, the method may include connecting the auxiliary blower inverterwith the auxiliary blower motor. Since the auxiliary blower may berelated to engine operation and the engine may be operational duringthird mode, the auxiliary blower may be provided with electrical powerin order to provide forced-air cooling.

At 920, the method may include connecting the traction motor blowerinverter with the grid blower motor. During the third mode, since thegrid or the electrical power bus is receiving electrical power, the gridblower may be provided with electrical power in order to operate to gridblower to provide forced-air cooling, de-icing, anti-bernelling, etc.During the third mode, since the engine may be operational andelectrical power may be provided to the grid, operation of the blowersassociated with the engine and the grid may be prioritized over thetraction motor blower.

In some embodiments, during the different operating modes, the gridblower motor may be operated temporarily in a reverse direction forintake cleaning purposes such as when an intake of the grid blower isblocked by debris. It will be appreciated that since the blower motorsare connected to the inverters, electrical power may be applied to thegrid without operation of the blower motors. For example, the grid maybe powered without the blower running during light loads conditions,during low audible noise output conditions, or for preventingmoisture/ice formation on the grid.

It will be appreciated that connection of an inverter with a motor asdescribed in the above method may be achieved through control of statethe transfer switch, such as by a controller of the locomotive vehiclesystem. By connecting the inverters and motors to a transfer switch andcontrolling the state of the transfer switch based on the mode ofoperation of the locomotive vehicle system, distribution of electricalpower may be prioritized to components that are operational during theparticular operating mode. Accordingly, the amount of inverters for usewith the motors may be reduced and locomotive vehicle system productioncosts may be reduced.

In some embodiments, one or more AC blower motors and their invertersmay be replaced with a DC motor connected via a chopper or speed controlcircuit. Further, the transfer switch may be controlled to selectivelyconnect the DC motors with the chopper circuit based on operating mode.

Note that the example control and estimation routines and/or methodsincluded herein can be used with various system configurations. Thespecific routines described herein may represent one or more of anynumber of processing strategies such as event-driven, interrupt-driven,multi-tasking, multi-threading, and the like. As such, various actions,operations, or functions illustrated may be performed in the sequenceillustrated, in parallel, or in some cases omitted. Likewise, the orderof processing is not necessarily required to achieve the features andadvantages of the example embodiments described herein, but is providedfor ease of illustration and description. One or more of the illustratedactions, functions, or operations may be repeatedly performed dependingon the particular strategy being used. Further, the describedoperations, functions, and/or acts may graphically represent code to beprogrammed into computer readable storage medium in the control system.

This written description uses examples to disclose the invention,including the best mode, and also to enable any person skilled in theart to practice the invention, including making and using any devices orsystems and performing any incorporated methods. The patentable scope ofthe invention is defined by the claims, and may include other examplesthat occur to those skilled in the art. Such other examples are intendedto be within the scope of the claims if they have structural elementsthat do not differ from the literal language of the claims, or if theyinclude equivalent structural elements with insubstantial differencesfrom the literal languages of the claims.

1. A drive system for a grid blower of a vehicle comprising: anelectrical bus; a grid of resistive elements connected to the electricalbus, the grid of resistive elements configured to thermally dissipateelectrical power generated by a braking operation of the vehicle, theelectrical power being transmitted on the electrical bus to the grid ofresistive elements; an electrical power modulation device configured tomodify electrical power received from the electrical bus, an input ofthe electrical power modulation device connected across at least oneresistive element of the grid of resistive elements; and a grid blowermotor coupled to an output of the electrical power modulation device,wherein a speed of the grid blower motor varies based on the electricalpower that has been modified by the electrical power modulation device.2. The system of claim 1, wherein an input of the electrical powermodulation device is connected to taps on the electrical bus.
 3. Thesystem of claim 1, wherein the electrical power modulation device isconfigured to modify at least one of a frequency and a voltage of theelectrical power received from the electrical bus.
 4. The system ofclaim 1, wherein the electrical power modulation device is an inverterand the grid blower motor is an alternating current motor.
 5. The systemof claim 1, wherein the electrical power modulation device is aconverter and the grid blower motor is a direct current motor.
 6. Thesystem of claim 1, further comprising: a controller configured to causethe electrical power modulation device to vary electrical power outputto control a speed of the grid blower motor based on an operatingparameter.
 7. The system of claim 6, further comprising: a secondelectrical power modulation device configured to modify electrical powerreceived from the electrical bus; and a second grid blower motor coupledto an output of the second electrical power modulation device, wherein aspeed of the second grid blower motor varies based on the electricalpower that has been modified by the second electrical power modulationdevice; wherein the controller is further configured to cause theelectrical power modulation device to output electrical power at a firstphase and configured to cause the second electrical power modulationdevice to output electrical power at a second phase different from thefirst phase.